External 404 in docs

[jamesplease]

In the docs, the beginning of the chroma.bezier links out to this external resource: https://gka.github.io/chroma.js/#chroma-bezier , which is currently returning a 404. According to Wayback Machine it's been 404'd for some time.

It can be accessed by going back in time a bit through Wayback Machine. For example, here.

I'm happy to open a PR to resolve this if you have a preference for the right solution. The link could be removed, or set to the Wayback Machine link, or something else.

Thanks for reading!